Ferroelectricity from coupled cooperative Jahn-Teller distortions and octahedral rotations in ordered Ruddlesden-Popper manganates

Antonio Cammarata, James M. Rondinelli

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Density functional theory and group-theoretical methods are used to explore the origin for ferroelectricity in cation ordered LaSrMnO4 with the Ruddlesden-Popper structure. The equilibrium phase exhibits the polar Pca21 space group where small polar displacements of d4Mn3+ coexist with antiferrodistortive octahedral rotations and Jahn-Teller distortions. We find that the octahedral rotations and Jahn-Teller distortion stabilize the polar structure and induce polar displacements through high-order anharmonic interactions among the three modes, making LaSrMnO4 a hybrid-improper ferroelectric material. The rotations result from the ionic size mismatch between A cations and Mn whereas the Jahn-Teller distortions are energetically favored owing to the coupling between the local eg orbital polarization of the two nearest-neighboring Mn cations in the two-dimensional MnO2 sheets. Our results indicate that anharmonic interactions among multiple centric modes can be activated by cation ordering to induce polar displacements in layered oxides, making it a reliable approach for realizing acentric properties in artificially constructed materials.

Original languageEnglish (US)
Article number014102
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume92
Issue number1
DOIs
StatePublished - Jul 2 2015

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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